Low FPS and Stutters on Longer Flights

Been using SU4 since it came out and have been noticing that for flights less than 2 hours, I get great performance throughout (60fps, no stutters). On flights over 2 hours, I start to see my FPS drop steadily into the 20s and stutters during land become out of control. My CPU, RAM, and VRAM utilization look the same throughout the flight and aren’t anywhere close to 100% utilization. Can’t seem to find any settings that make a difference. Anyone else experiencing this? Any recommendations?